1. Field of Invention
The present invention relates to a testing method. More particularly, the present invention relates to a monitor method for testing probe pins used in a WAT (wafer acceptance test) process.
2. Description of Related Art
After completing manufacturing processes, dies on the wafer should be verified. Generally, a probe card with probe pins is used to test the dies. The probe pins on the probe card directly contact the wafer to perform the testing process. Since the probe pins directly contact the wafer, the probe pins are easily deformed. Moreover, some materials such as oxide, photoresist residues or solvent contamination are usually adhered on the probe pins due to the direct contact. Therefore, erroneous data may be obtained by using the problem probe pins.
FIG. 1 is a schematic diagram showing probe pins with various problems including a short, unstable contact and deformity.
Referring to FIG. 1, probe pins 12a, 12b, 12c, 12d, 12e are formed on a probe card 10. The probe pin 12a is normal. Material 14a is adhered on the probe pin 12b, and material 14b is adhered on the probe pins 12c, 12d. The materials 14a, 14b are, for example, oxide, photoresist residues or solvent contamination. Because of the material 14b, the probe pin 12c and 12d are shorted. The probe pin 12e is deformed; thus, the probe pin 12e cannot contact the wafer during the testing process.
Since the dimension of the probe pin is small, it is difficult to identify the above problems. Moreover, many probe pins are formed on a probe card; thus, it is difficult to identify a particular probe pin. Consequently, erroneous results are obtained during the testing process by using the problem probe pins.